This invention relates generally to drilling devices and, more particularly, to an expandable diameter drill bit having a torsion spring for biasing one or more blades outwardly such that a hole being drilled is enlarged.
Rotary drilling devices are used to bore a generally cylindrical hole into the ground to a depth at which a fluid may be extracted, such as water, oil, natural gas, or the like. Sometimes an existing well needs to be re-drilled, cleaned out, or the diameter expanded. A rotary drill may include one or more blades that scrape or dig into the ground surface as the drill rotates. The blades often wear out, break, or otherwise fail and must be replaced, especially when operated at high speed. Another problem with drilling devices is that a drill bit having one diameter may be used and then replaced with a drill bit having a larger diameter in order to increase the diameter of the well.
Although existing rotary drilling devices are presumably effective to drill subsurface wells, they are less effective in operating to increase the diameter of the hole. For instance, some expanding diameter drill bits urge their blades outwardly by centrifugal force and, as a result, require high speed rotation which may not be possible in some subsurface conditions or if debris is building up too quickly within a hole.
Therefore, it would be desirable to have an expandable diameter drill bit having one or more blades that are automatically biased outwardly by respective torsion springs. Further, it would be desirable to have an expandable diameter drill bit having a construction that is less susceptible to blade breakage and more effective in cutting through rock.